A fluid flow process (flow process) includes any process that involves the flow of fluid through pipes, ducts, or other conduits, as well as through fluid control devices such as pumps, valves, orifices, heat exchangers, and the like. Flow processes are found in many different industries such as the oil and gas industry, refining, food and beverage industry, chemical and petrochemical industry, pulp and paper industry, power generation, pharmaceutical industry, and water and wastewater treatment industry. The fluid within the flow process may be a single phase fluid (e.g., gas, liquid or gas/liquid mixture) and/or a multi-phase mixture (e.g. paper and pulp slurries or other solid/liquid mixtures). The multi-phase mixture may be a two-phase liquid/gas mixture, a solid/gas mixture or a solid/liquid mixture, gas entrained liquid or a three-phase mixture.
Various sensing technologies exist for measuring various physical parameters of fluids in an industrial flow process. Such physical parameters may include, for example, volumetric flow rate, composition, gas volume fraction, consistency, density, and mass flow rate.
One such sensing technology is described in U.S. Pat. No. 6,609,069 to Gysling, entitled “Method and Apparatus for Determining the Flow Velocity Within a Pipe”, which is incorporated herein by reference. The '069 patent describes a method and corresponding apparatus for measuring the flow velocity of a fluid in an elongated body (pipe) by sensing vortical disturbances convecting with the fluid. The method includes the steps of providing an array of at least two sensors disposed at predetermined locations along the elongated body, each sensor for sampling the pressure of the fluid at the position of the sensor at a predetermined sampling rate; accumulating the sampled data from each sensor at each of a number of instants of time spanning a predetermined sampling duration; and constructing from the accumulated sampled data at least a portion of a so called k-ω plot, where the k-ω plot is indicative of a dispersion relation for the propagation of acoustic pressures emanating from the vortical disturbances. The method also includes the steps of identifying a convective ridge in the k-ω plot; determining the orientation of the convective ridge in the k-ω plot; and determining the flow velocity based on a predetermined correlation of the flow velocity with the slope of the convective ridge of the k-ω plot.
Such sensing technology is effective in determining various parameters of a fluid flow within a pipe. However, as with any computationally complex process, there remains a desire to increase computational efficiency, accuracy, and robustness.
Unfortunately however, in some situations flow measurements may be corrupted or they may not be able to be obtained at all due to the presence of unwanted signals masking the convective ridge (or vortical flow ridge). This unwanted energy can obscure or mask the energy of the convective ridge, and therefore, make it difficult or even impossible to isolate the energy of the convective ridge to determine the slope of the ridge. In a similar fashion to the flow measurements regarding the convective ridges, the measurements regarding the acoustic ridges also typically include unwanted signals that may mask or prevent the measurement altogether of the acoustic ridge. This is undesirable because the slope of the convective ridge is indicative of velocity of the fluid flow within the pipe and the slope of the acoustic is indicative of the speed of sound of the fluid.